U.S. Interior Secretary Ken Salazar said in a memorandum that problems were identified "in recent weeks" with blowout preventers on BP Plc's relief wells, which are seen as the only proven way to kill the Gulf of Mexico oil leak.
In a 29-page memo to Michael Bromwich, director of the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) dated Monday, Salazar said "performance problems" with the blowout preventers were found when new testing requirements were imposed after the April 20 blowout that preceded the gushing leak.
The blowout preventers passed new tests after the problems were fixed, BOEMRE spokesman Nicholas Pardi said on Tuesday.
The Department of the Interior "is closely monitoring the drilling of the relief wells to ensure safety," Pardi said.
Salazar said in the memo that the discovery provided "more evidence that prior testing requirements were inadequate."
The first of two relief wells begun in May is expected to intercept the blown-out well by the end of July and plug it with drilling mud and cement by mid-August, BP said.
Pardi said the first round of tests on the blowout preventers showed leaking or failed valves, a shuttle valve that shouldn't have been installed that caused another test failure and a broken connection that stopped a casing shear ram from closing.
Such rams cut through and seal pipes in wells to prevent blowouts.
The memorandum was revealed as BP continues to struggle to plug the leaking well.
Transocean Ltd. owned the blowout preventer that failed, leading to the explosion of its Deepwater Horizon oil rig that was drilling BP's stricken Macondo well. Eleven workers died. The failure of that blowout preventer is under investigation.
Transocean spokesman Guy Cantwell said in an email that the issues with the blowout preventers for the relief wells were now resolved.
As the well owner and drilling plan designer, BP is responsible for the spill, from stopping the leak to cleaning up environmental and economic damage along the Gulf Coast.